It is known that missiles with seeker heads provided with infra red radiation detectors constitute a danger to military heavier than air machines, particularly to aircraft and helicopters provided with gas turbine engines, since the hot metallic members which these heavier than air machines have downstream of their turbine engine(s), and which are either the rear parts of these engines such as their outlet nozzle, or are metallic parts which are swept over and heated up by the hot plume of exhaust gas from the turbine engine, as well as the hot exhaust gas plume itself, constitute substantial sources of infra red radiation emission.
For this reason, it has already been proposed to suppress, or at least to reduce or attenuate to the greatest extent possible, though simultaneously without detracting too much from the operation or performance of the gas turbine engine, the infra red emission from these hot metallic parts and the plume of hot gas, on the one hand by masking the hot parts from the "view" of the missile, whatever the relative position of the missile relative to the heavier than air machine, and on the other hand by ensuring dilution of the hot exhaust gas plume with fresh ambient air, with the object of lowering its temperature sufficiently.